Department of Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, United States.
Department of Civil and Environmental Engineering, Manhattan College, Riverdale, NY 10471, United States.
Environ Pollut. 2017 Jun;225:524-533. doi: 10.1016/j.envpol.2017.01.088. Epub 2017 Mar 16.
Phytoextraction is a green remediation technology for cleaning contaminated soils. Application of chelating agents increases metal solubility and enhances phytoextraction. Following a successful greenhouse experiment, a panel study under field weather elucidated the efficiency of the chelating agent ethylenediaminedisuccinic acid (EDDS) on phytoextraction of lead (Pb) by vetiver grass, a hyperaccumulator of Pb, and a nonaccumulator fescue grass from residential soils contaminated with Pb-based paint from Baltimore, MD and San Antonio, TX. Three soils from each city with Pb content between 1000 and 2400 mg kg were chosen for the panel study. Sequential extraction revealed that Fe-Mn oxide (60-63%) and carbonate (25-33%) fractions of Pb dominated in Baltimore soils, whereas in San Antonio soils, Pb was primarily bound to the organic fraction (64-70%) because organic content was greater and, secondarily, to the Fe-Mn oxide (15-20%) fraction. Vetiver and fescue grasses were transplanted and grown on wood panels in the field with EDDS applied after 3 months and 13 months. Soil and leachate results indicated that EDDS applications increased Pb solubility in soils. Plant tissues results indicated enhanced the uptake of Pb by vetiver and showed that EDDS application promoted translocation of Pb from root to shoot. Average Pb concentration increased by 53% and 203% in shoots and by 73% and 84% in roots of vetiver after the first and second applications of EDDS, respectively. Concentrations in roots and shoots increased in all tested soils, regardless of soil pH or clay content. After the second application, average Pb concentrations in vetiver were higher than those in fescue by 3.6x in shoots and 8.3x in roots. Visual phytotoxic symptoms from increased bioavailable Pb from EDSS applications were observed in fescue but not in vetiver. This study demonstrated the potential of a chemically-catalyzed phytoremediation system as a cleanup method for lead-contaminated soils.
植物提取是一种绿色修复技术，用于清洁受污染的土壤。螯合剂的应用增加了金属的溶解度，增强了植物提取的效果。在温室成功实验后，一项野外天气条件下的小组研究阐明了螯合剂乙二胺二琥珀酸（EDDS）对受马里兰州巴尔的摩和德克萨斯州圣安东尼奥市含铅涂料污染的住宅土壤中 Pb 的超积累植物香根草和非积累植物黑麦草的植物提取效率的影响。从每个城市选择了三种 Pb 含量在 1000 到 2400mg/kg 之间的土壤进行小组研究。连续提取表明，Fe-Mn 氧化物（60-63%）和碳酸盐（25-33%）是巴尔的摩土壤中 Pb 的主要赋存形态，而在圣安东尼奥土壤中，Pb 主要与有机部分（64-70%）结合，其次是 Fe-Mn 氧化物（15-20%）部分。香根草和黑麦草被移植到野外的木板上，并在 3 个月和 13 个月后用 EDDS 进行了生长。土壤和淋出液结果表明，EDDS 的应用增加了土壤中 Pb 的溶解度。植物组织的结果表明，EDDS 的应用增强了香根草对 Pb 的吸收，并表明 EDDS 的应用促进了 Pb 从根部向地上部分的转移。EDDS 第一次和第二次应用后，香根草地上部分的 Pb 浓度分别增加了 53%和 203%，根部的 Pb 浓度分别增加了 73%和 84%。在所有测试的土壤中，无论土壤 pH 值或粘土含量如何，根和地上部分的浓度都增加了。第二次应用后，香根草地上部分的 Pb 浓度比黑麦草高 3.6 倍，根部高 8.3 倍。EDSS 应用增加了生物可利用 Pb，导致黑麦草出现可见的植物毒性症状，但香根草没有。本研究证明了化学催化植物修复系统作为一种受 Pb 污染土壤的清洁方法的潜力。
